Seeking 2nd Opinion: - Surge Under Load Diagnosed As Possible Wastegate Issue.

[BCCairns]

Hey Guys, seeking some wisdom / advice.

A bit about the car. The car is a 99 Stage RS4-S factory manual has turbosmart duel stage boost and FMIC, boost running at 4pound and 9 pound, other then that its stock.

The problem i'm having is under load around 4000 and 6000 rpm i get a stuter / surge. It doesn't happen all the time but I would say 40% of the time sometimes it's v.minor and other times it is more pronounced. Not being a mechanic and reading skylines Australia I thought must be coil packs.

I took the car to a mechanic mate of mine today to see what he thought and to pull the coil packs (standard) and plugs (iridium) for a check. He took it for a drive and was 100% sure it wasn't a missfire and though it felt like a limiter feel. He then checked the ECU using a diagnostics computer and found 55 No fault found which indicates not a missfire problem.

He then asked the apprentice cos he had some experience with skylines, the apprentice reckons its a wastegate problem and to test it remove the vacuum hose of the standard blow off valve and plug the hose with a bolt, take it for a drive and see if it happens (the vacuum hose pic is below). So I did that and although it had less power it didn't have that stutter problem. (What does this test prove, does it prove it is a shagged wastegate? Im no mech so I got no idea)

Any thoughts as to what it could be? Wastegate, acutuator, something else?

Cheers,

Brad from Cairns

Edited May 15, 2010 by BCCairns

[streatracer]

He then asked the apprentice cos he had some experience with skylines, the apprentice reckons its a wastegate problem and to test it remove the vacuum hose of the standard blow off valve and plug the hose with a bolt, take it for a drive and see if it happens. So I did that and although it had less power it didn't have that stutter problem. (What does this test prove, does it prove it is a shagged wastegate? Im no mech so I got no idea)

?????? Well im no mechanic either but that is a little weird. Although being able to run 4psi is also weird? perhaps ur guage reads a little low?

I can't see how that would prove the wastegate is stuffed. It really does sound like coilpacks (or possibly fuel pump?) do you know anyone who would lend you a set to try?

Personally I would find a dedicated performance workshop and get them to have a look. Any decent workshop should know RB25s

(also pretty sure error code 55 indicates no errors found lol so your mechanic might not be too savvy with the imports)

Edited May 15, 2010 by streatracer

[QWK32]

the only thing that removing the vac line off the BOV proves is the apprentice isn't as crash hot on skylines as he thinks, blocking the BOV line will have no influence on the wastegate. without that vac line the BOV could now be blowing open under boost hence the lack of power you feeling after blocking it.

it still could be a slight breakdown/misfire issue, it won't show up on the DTC's unless a coil pack or PTU completely fails, thats why you have no error codes. when you say its like a limiter how does it feel? i mean, is it a violent stutter, a complete engine cut, or just like the power has flattened out a bit?

A couple things that would be worth doing are, change the plugs out for a set of coppers gapped to 0.8, and change your fuel filter if you haven't already.

Edited May 15, 2010 by QWK32

[BCCairns]

Cheers for ya thoughts, the 4pound low boost is a bit of a guess. Its tricky as the stock boost gauge in the middle of the dash isn't working and the aftermarket boost pressure gauge seems to be around 4 when accelerating (its the wifes car so i use the low boost setting =).

[StealthX]

I think that apprentice mechanic has no idea about turbo systems. So long as the car makes the same amount of boost through the area that you have the problem (4k - 6k) it won't be a wastegate problem at all. The only thing the wastegate could do wrong is cause a spike in boost and you are hitting a condition called R&R, it's a factory safety thing so protect against spikes in boost, basically retards the timing and adds heaps of fuel, and you'll loose power there. But if you are still seeing 4psi, then that can't be the problem.

I reckon you might have a poor spark, try gapping down your plugs (take the plugs out and make the gap between the electrode and the plug smaller. This should improve the strength of the spark.

[BCCairns]

Cheers heaps Josh thats helped me think about the prob a bit differently.

If I had to chose between 'violent stutter, a complete engine cut, or just like the power has flattened out a bit' I'm leaning towards power flattened out a bit, and sometimes mild, stutter when it powers back. Because it only happens under full load if the power flattened out and it kicks in then the whole things would seem a little harsh.

As for the blocking of the BOV vacuum from what your saying if it was underboosting then it wouldn't be putting load on the ignition and as such no missfire. Which leaves me thing coils and plugs (which seems so common)

Thanks heaps again.

[pipster11]

mine surges under heavy load sometimes - not massively but its there

i'd say its coilpacks starting to let go

the dont suddenly fail, just get worse

if you can find some liquid neoprene you can coat the coilpacks in that to insulate them and hold them off from failing for a bit longer or high temp silicone is good too

or just replace them - yellowjackets will set you back around the $400 mark and will be good for quite a few years to come

splitfires will last a bit longer but cost more

[BCCairns]

I think that's the only direction I can go.. I'll do some copper plugs at 0.8 and neoprene up the coil packs and see how i go. I'll let ya know.

Went for a few beers last night with me mech mate and he just doesn't reckon its a missfire.. He said he could be wrong because hasn't worked on Skylines but he said it ain't like any hundreds of missfires he has felt and fixed on run of the mill cars e.g Fords, holden and NA engines. Makes it hard cos I have no idea what varying degrees of missfires feel like.. And its realy hard to describe a problem to diagnose over the internet.

So I went looking on the net and found this video on youtube, and as far as video goes (to varying degrees) the popping / stuttering is exactly whats happening to me. http://www.youtube.com/user/syncore34#p/u/9/EOWmMYv86_w

wish I could find this Syncore34 guy see if he fixed it.

Edited May 16, 2010 by BCCairns

[pipster11]

it cant hurt to do that

i rate coppers better than platinums or iridiums

and .8mm is a good gap to go to if your uncertain if its coilpacks

failing coilpacks usually go out slowly in skylines so they could easily be on the way out

[BCCairns]

Cheers guys you were all on the money, nothing to do with a wastegate etc..

So tonight I threw in some copper NGk's gapped at .8mm. Visual inspection of the coils looked pretty good. Could see 1 coil had some feint white lines from what looked to be a tinny gap in a seem. It's the wifes car so i needed to have it on the road tomorrow so I just wrapped that coil with electrical tape.

I then set off for a 10 minute test run, boosted through 4k to 6k rpm no probs at 8psi. After about 6 mins of boosting around, it did start hesitating slight, but nothing like and it still boosted and powered through the hesitations.

So conclusions it's got to be one or more coil packs braking down. Looks like I will be breaking the sealeys 401 silicon on the weekend, then failing that forking out for yellowjakets.

Will keep you posted

[chuckie]

Cheers guys you were all on the money, nothing to do with a wastegate etc..

So tonight I threw in some copper NGk's gapped at .8mm. Visual inspection of the coils looked pretty good. Could see 1 coil had some feint white lines from what looked to be a tinny gap in a seem. It's the wifes car so i needed to have it on the road tomorrow so I just wrapped that coil with electrical tape.

I then set off for a 10 minute test run, boosted through 4k to 6k rpm no probs at 8psi. After about 6 mins of boosting around, it did start hesitating slight, but nothing like and it still boosted and powered through the hesitations.

So conclusions it's got to be one or more coil packs braking down. Looks like I will be breaking the sealeys 401 silicon on the weekend, then failing that forking out for yellowjakets.

Will keep you posted

G`Day ,

Silicon ???

May be try URETHANE SEAL COAT,i use this on my COILPACK`S & dose great JOB & is not MESSIE like SILICONE,

Done few set`s for mate`s & works great, spray them any colour you like once coated,

i have POSTED in few theard`s so hope it`s a HELP,

+ iam now trying to use a FIBRE WASHER under COILPACK`S to reduce the HEAT in to COIL`S hope it work`s & may help other`s again,

Cheer`s Chuckie .

[lachlanw]

GET A REAL BOOST GAUGE

standard one + boost controller = fail

[lachlanw]

read this

http://www.skylinesaustralia.com/forums/Dy...ry-t320073.html

post # 11 from STATUS

r34 is even worse than r33 ecu

my car is the same as yours . i have it right on the limit of doing it . depends on the weather

[lachlanw]

G`Day ,

Silicon ???

May be try URETHANE SEAL COAT,i use this on my COILPACK`S & dose great JOB & is not MESSIE like SILICONE,

Done few set`s for mate`s & works great, spray them any colour you like once coated,

i have POSTED in few theard`s so hope it`s a HELP,

+ iam now trying to use a FIBRE WASHER under COILPACK`S to reduce the HEAT in to COIL`S hope it work`s & may help other`s again,

Cheer`s Chuckie .

the fibre washer wont do much . might make matters worse actualy as the spark plug boot wont fit on the sparkplug properly

once they have been cooked for 10 years they are f**ked .

fibre washers would be preventitve . not corrective

[BCCairns]

Cheers chukie, I will give that urethane seal a go for sure. I did forget to mention I do have a After market boost gauge.

So Lachlan are you saying you can't boost reliably above 8psi on your s2 rs four s? I went for a drive today, at 8psi nothing was failing for a good 30 mins so I thought bonus I will up the boost. I upped it 2 clicks so I guess that would be around 9psi and it consistentl hesitate in 2 spots around 5500 and 6500, it was nothing like the original prob I had, is this the r&r? or the thing u refer to in post 11 at

http://www.skylinesaustralia.com/forums/Dy...ry-t320073.html

[chuckie]

Hi Well i will try Washer`s TO SEE IF it will help & try few more bit`s later on ,ONLY looking to see what WORK`S & WHAT DON`T

just need to try different thing`s see what happen`s ,COILPACK only have very small crack`s so eruthane will fill them & work`s well,so far lol.

Cheer`s Chuckie.

[QWK32]

Cheers chukie, I will give that urethane seal a go for sure. I did forget to mention I do have a After market boost gauge.

So Lachlan are you saying you can't boost reliably above 8psi on your s2 rs four s? I went for a drive today, at 8psi nothing was failing for a good 30 mins so I thought bonus I will up the boost. I upped it 2 clicks so I guess that would be around 9psi and it consistentl hesitate in 2 spots around 5500 and 6500, it was nothing like the original prob I had, is this the r&r? or the thing u refer to in post 11 at

http://www.skylinesaustralia.com/forums/Dy...ry-t320073.html

with the reference to the link, if your engine is 100% ie no dodge coils, there will still be a small flat spot around 4800-5200 rpm, almost like power eases off for a sec then kicks back in. the engine will seem to be running fine and rev smoothly during this flat spot. i could really notice it at 11psi on stock maps and turbo.

when a coil pack is breaking down / miss-firing you will notice the engine run a little rough, probably more noticeable with a aftermarket exhaust system where you will hear the engine's note stutter, cough or even backfire.

you wont be feeling R&R if you say it is only hesitating during a small rpm range and running fine and "full" powered the rest. once you hit R&R the ecu will stay on the knock maps for a while (i think until restart), so the car will feel sluggish and slow through the whole rev range while in R&R.

i've seen chuckies post with the pics of his coil packs sprayed in that crc urethane stuff he is talking about. that stuff looks like it seals the coils up really well and about 100 time neater than pumping silicone all over them. i say try that first, it cant hurt and its cheap and easy.

[BCCairns]

Sound like a plan, I'll do these coils then worry about getting to 10+psi.. I forgot to mention in mods I do have 3"inch system from the manifold (*blames forgetting to mention earlier on new born baby distractions =)

I've been searching the forums and it seems like something is fishy with Rs4 s and getting the boost above 7 psi due to sensitive ecu and boost limiter solenoid so thats a likely cause of my new higher boost problem. http://www.skylinesaustralia.com/forums/Bo...43#entry4940243

think i mite have to get a nisstune if i want to get to 10psi. or do that plug the tube to solenoid mod but im not so sure how safe that is ?

thanks again, for ya help ppl

Edited May 20, 2010 by BCCairns

[pipster11]

i have no problems here running 10psi on my RSfour S

oh, and that urethane stuff is the shit

[lachlanw]

same model of car

i run .7 bar and its sweet